Logical Reasoning - Number Series - Discussion
Discussion Forum : Number Series - Type 1 (Q.No. 19)
Directions to Solve
In each series, look for the degree and direction of change between the numbers. In other words, do the numbers increase or decrease, and by how much
19.
Look at this series: 8, 6, 9, 23, 87 , ... What number should come next?
Answer: Option
Explanation:
8 x 1 - 2 = 6
6 x 2 - 3 = 9
9 x 3 - 4 = 23
23 x 4 - 5 = 87
87 x 5 - 6 = 429 ...
Discussion:
110 comments Page 3 of 11.
Narendra Padhan said:
1 decade ago
It is the best method of develop your knowledge.
The Helpful Brit said:
1 decade ago
General form is X(n+1) = (X (n)*n) - (n+1) ). Where X(n) is the term number in the series, X (n+1) is the subsequent term and n is the element position aka as index.
All algebraic terms will always represent integer values.
X(n); n(X (n)*n)-(n+1)) = X(n+1).
X(1) = 8; n = 1((8)*(1))-(2)) = 6.
X(2) = 6; n = 2((6)*(2))-(3)) = 9.
X(3) = 9; n = 3((9)*(3))-(4)) = 23.
X(4) = 23; n = 4((23)*(4))-(5)) = 87.
X(5) = 87; n = 5((87)*(5))-(6)) = 429.
Therefore.
X(6) = 429; n = 6((429)*(6))-(7)) = 2567.
All algebraic terms will always represent integer values.
X(n); n(X (n)*n)-(n+1)) = X(n+1).
X(1) = 8; n = 1((8)*(1))-(2)) = 6.
X(2) = 6; n = 2((6)*(2))-(3)) = 9.
X(3) = 9; n = 3((9)*(3))-(4)) = 23.
X(4) = 23; n = 4((23)*(4))-(5)) = 87.
X(5) = 87; n = 5((87)*(5))-(6)) = 429.
Therefore.
X(6) = 429; n = 6((429)*(6))-(7)) = 2567.
Nityusha said:
1 decade ago
Any other simpler way?
Gaurav Sharma said:
1 decade ago
So easy but starting point is very tough.
Amit said:
1 decade ago
I have solved all series problems its very easy only two problems are moderate.
Arj said:
1 decade ago
Is there any other way to solve the series?
Bhoi said:
1 decade ago
This one is very tough and also the series is not so predictable.
Karishma said:
1 decade ago
Because 6+9+23!=87.
Prithvi said:
1 decade ago
Understand the given solution we can easy to solve.
Aruna said:
1 decade ago
When we saw that answer it looks like easy only but how we can recognize this is in this format it is like confusing question.
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